Over the years considerable work has been devoted to additives for controlling (preventing or reducing) deposit formation in the fuel induction systems of spark-ignition internal combustion engines. In particular, additives that can effectively control fuel injector deposits, intake valve deposits and combustion chamber deposits represent the focal point of considerable research activities in the field and despite these efforts, further improvements are desired particularly in view of further advances in engine technology for improved fuel economy and engine wear.
DIG technology is currently on a steep developmental curve because of its high potential for improved fuel economy and power. Environmentally, fuel economy benefits of such engines translate directly into lower carbon dioxide emissions. However, DIG engines may encounter problems different from those of the conventional gasoline engines due to the direct injection of gasoline into the combustion chamber.
One of the major obstacles in DIG engine development was spark plug fouling. A narrow spacing configuration, where the fuel injector sat close to the spark plug, allowed easy fuel ignition as the fuel directly hit the plug. However, such close spacing causes soot to accumulate on the plug, eventually leading to spark plug fouling.
Another problem with DIG engines is related to the smoke exhausted mainly from the part of the mixture in which the gasoline is excessively rich, upon stratified combustion of the filet. The amount of soot produced is greater than that of a conventional engine, thus a greater amount of soot may enter the lubricating oil through combustion gas blow by.
As different, more advanced engine types enter service worldwide, a fuel to power not only traditional multi-port fuel injected engines, but also gasoline direct injection engines may be required. The additives which work well as detergents in MPI engines will not necessarily work well in GDI engines, and as such additional detergents prepared especially for DIG engines may be required as a “top-treat” type additive or as an after-market fuel supplement.
In addition to the above, the present generation of DIG engine technologies have experienced deposit problems. Areas of particular concern are fuel rails, injectors, combustion chamber (CCD), crankcase soot loadings, and intake valves (IVD). Deposits in the intake manifold come in through the PCV valve and exhaust gas recirculation (FUR). Since there is no liquid filet wetting the back of the intake valves, these deposits build up quite quickly and can cause reduction in fuel economy over time if they are not removed.
Yet another problem with newer gasoline engine is increased wear of fuel contacted components of the engine. In particular, increasing amounts of oxygenates in the gasoline compositions from about 0 to about 85 percent by volume tend to increase wear of fuel contacted components in the engine.
In view of the foregoing, various embodiments of the disclosure provide fuel compositions for a spark-ignition internal engine, a fuel additive package for a spark-ignition engine, a method of operating a spark-ignition engine, and a method of reducing intake valve deposits or improving antiwear performance in a spark-ignition engine. The additive package includes a Mannich base detergent mixture that comprised of a first Mannich base detergent component derived from a di- or polyamine and a second Mannich base detergent component derived from a monoamine. A weight ratio of the first Mannich base detergent to the second Mannich base detergent in the mixture ranges from about 1:6 to about 3:1, such as from 1:4 to 2:1 or from 1:3 to 1:1.
In one embodiment of the disclosure, a fuel additive package is provided for a spark-ignition engine that includes, a) a first Mannich base detergent component derived from a di- or polyamine, (b) a second Mannich base detergent component derived from a monoamine, (c) an antiwear component, and (d) optionally, a carrier fluid component selected from the group consisting of a polyether monool and polyether polyol. A weight ratio of the first Mannich base detergent to the second Mannich base detergent in the fuel additive package ranges from about 1:6 to about 3:1, such as from 1:4 to 2:1 or from 1:3 to 1:1.
In another embodiment of the disclosure, a method for operating a spark-ignition engine on an unleaded fuel composition is provided. The method includes supplying to the engine a fuel composition that includes (a) a gasoline fuel, (b) a first Mannich base detergent derived from a di- or polyamine, (c) a second Mannich base detergent derived from a monoamine, (d) an antiwear component, and (e) optionally, a succinimide detergent. A weight ratio of (b) to (c) in the fuel ranges from about 1:6 to about 3:1, such as from 1:4 to 2:1 or from 1:3 to 1:1. The fuel composition is introduced into the engine for combustion thereof, and the engine is operated on the fuel.
Yet another embodiment of the disclosure, there is provided an unleaded fuel composition for a spark-ignited engine. The fuel composition includes (a) a major amount of a gasoline fuel, (b) a minor amount of a first Mannich base detergent derived from a di- or polyamine, (c) minor amount of a second Mannich base detergent derived from an di-alkyl monoamine, (d) an antiwear component selected from the group consisting of a hydrocarbyl amide and a hydrocarbyl imide, and (I) a polyether carrier fluid. A weight ratio of the first Mannich base detergent to the second Mannich base detergent in the fuel composition ranges from 1:6 to about 3:1, such as from 1:4 to 2:1 or from 1:3 to 1:1.
Another embodiment of the disclosure a method for improving at least one of reducing intake valve deposits or improving antiwear performance in a spark-ignition engine. The method includes providing a fuel composition that includes (a) a major amount of a gasoline fuel containing ethanol, (b) a minor amount of a first Mannich base detergent derived from a di- or polyamine, (c) minor amount of a second Mannich base detergent derived from an di-alkyl monoamine, (d) an antiwear component selected from the group consisting of a hydrocarbyl amide and a hydrocarbyl imide, and (e) a polyether carrier fluid comprising C6-C20 alkylphenol propoxylate. A weight ratio of the first Mannich base detergent to the second Mannich base detergent in the fuel composition ranges from 1:6 to about 3:1 such as from 1:4 to 2:1 or from 1:3 to 1:1. The fuel composition is supplied to the engine and combusted in the engine.
Accordingly, the Mannich base detergent of embodiments of the disclosure includes at least two different Mannich base detergents as described in more detail below. Advantages of the disclosed embodiments, may include, but are not limited to, one or more of improved injector performance, reduced engine deposits, improved antiwear performance of moving parts in the engine, improved fuel economy, reduced intake valve deposits, reduced injector deposits and/or reduced soot formation in spark-ignition engines, especially DIG engines, and reduced fuel plugging. Further benefits and advantages may be evidence from the following detailed description of the disclosed embodiments.
It will be appreciated that the terminology “deposit inhibitor compound” can be a compound, the presence of which in the fuel composition, directly or indirectly results in controlled, i.e., reduced or eliminated, deposits and/or soot formation in the engine.